DOI

Although many lake restoration projects
have led to decreased nutrient loads and increased
water transparency, the establishment or expansion of
macrophytes does not immediately follow the
improved abiotic conditions and it is often unclear
whether vegetation with high macrophyte diversity
will return. We provide an overview of the potential
bottlenecks for restoration of submerged macrophyte
vegetation with a high biodiversity and focus on the
biotic factors, including the availability of propagules,
herbivory, plant competition and the role of remnant
populations. We found that the potential for restoration
in many lakes is large when clear water conditions
are met, even though the macrophyte community
composition of the early 1900s, the start of humaninduced
large-scale eutrophication in Northwestern
Europe, could not be restored. However, emerging
charophytes and species rich vegetation are often lost
due to competition with eutrophic species. Disturbances
such as herbivory can limit dominance by
eutrophic species and improve macrophyte diversity.
We conclude that it is imperative to study the role of
propagule availability more closely as well as the
biotic interactions including herbivory and plant
competition. After abiotic conditions are met, these
will further determine macrophyte diversity and define
what exactly can be restored and what not.